Field of the Invention
This invention relates to procedures and equipment for profiling and jointing of pipes, and relates more particularly but not exclusively to methods and apparatus for the shaping and/or expansion and/or conjoining of tubular casings in wells.
In the hydrocarbon exploration and production industry there is a requirement to deploy tubular casings in relatively narrow-bore wells, and to expand the deployed casing in situ. The casing may require to be expanded throughout its length in order to line a bore drilled through geological material; the casing may additionally or alternatively require to be expanded at one end where it overlaps and lies concentrically within another length of previously deployed casing in order to form a swaged joint between the two lengths of casing. Proposals have been made that a slotted metal tube be expanded by mechanically pulling a mandrel through the tube, and that a solid-walled steel tube be expanded by hydraulically pushing a part-conical ceramic plunger through the tube. In both of these proposals, very high longitudinal forces would be exerted throughout the length of the tubing, which accordingly would require to be anchored at one end. Where mechanical pulling is to be employed, the pulling force would require to be exerted through a drillstring (in relatively large diameter wells) or through coiled tubing (in relatively small diameter wells). The necessary force would become harder to apply as the well became more deviated (i.e. more non-vertical), and in any event, coiled tubing may not tolerate high longitudinal forces. Where hydraulic pushing is to be employed, the required pressure may be hazardously high, and in any event the downhole system would require to be pressure-tight and substantially leak-free. (This would preclude the use of a hydraulically pushed mandrel for the expansion of slotted tubes). The use of a fixed-diameter mandrel or plug would make it impracticable or impossible to control or to vary post-deformation diameter after the start of the expansion procedure.
It is therefore an object of the invention to provide new and improved procedures and equipment for the profiling or jointing of pipes or other hollow tubular articles, which obviate or mitigate at least some of the disadvantages of the prior art.
In the following specification and claims, references to a “pipe” are to be taken as references to a hollow tubular pipe and to other forms of hollow tubular article, and references to “profiling” are to be taken as comprising alteration of shape and/or dimension(s) which alteration preferably takes place substantially without removal of material.